[Day2_69Z]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cook_dw</div><div class="ubbcode-body">Thanks for the info! The other header has 325L. So not sure about the round and oval.</div></div>

Round and oval are the same definition for round/oval port.... which only applies to the intake ports. The exhaust ports on factory heads are the same for square/ rectangle ports as round .. ...stock exhaust manifolds confirm that.
Aftermarket or GM Aluminum heads may have square ports/D ports and or raised ports.
A funny thing is,
what side are the L &amp; R on ? R-Right
L- left ... ????
Head flanges may have been different for R &amp; L due to water temp sending units or something like that.

Those exhaust ports/flanges on your headers are quite large for the period....they may be High Performance/ Pro type class for heavily modified heads.

The best header manufacturers were on top of racers needs and most built custom order items, such as Doug's,
Jardine, Hedman etc. Hooker was more out of the box kinda supplier.

Do some more asking of Header Manufacturing and parts #'s.
something will come to light.